Conventional communication systems employ RF power amplifies for controlling the magnitude of transmitted signals. Such RF power amplifiers sometimes require the detection of the level of input signals to, or output signals from, said amplifiers, in order to allow the adaptation of their performance to varying signal levels. Such requirement is disclosed, for example, in WO 01/67598, which discloses an RF power amplifier that changes its operation mode whenever the level of the input signal to said power amplifier exceeds a predetermined threshold level. Therefore, prompt reliable detection of signal levels is essential for optimal operation of such amplifier.
A conventional technique for the detection of RF signals employs diode-based detector based detectors. However, such detector diodes are usually capable of handling low-power signals, in the order of mW, which are typical levels in various laboratory equipment and in communications receivers. In recent years, high performance RF power amplifiers have been developed, which are capable of handling transmission in the KW power range. Consequently, the ancillary circuitry designed for properly controlling such power amplifiers are often required to detect much higher levels of RF signals, such as to output pulses, in the order of several Watts. Therefore, whenever diode-based detectors are used to detect the envelope of an RF signal, this envelope should also be amplified (since the actual detected signal is the mean value of the envelope), resulting in a substantial delay, which is unacceptable when fast occurring changes in the amplitude of the RF signal should be detected and used for control.
The method described above has not yet provided satisfactory solutions to the problem of real-time amplitude detection of high level RF signals, amplified by an RF power amplifier.
It is an object of the present invention to provide an apparatus for detecting the amplitude of high level RF signals, essentially without delay.
It is still another object of the present invention to provide an apparatus for detecting the amplitude of high level RF signals, and outputting corresponding high-level envelope signals.
Other objects and advantages of the invention will become apparent as the description proceeds.